Mold for forming solder distal tip for guidewire

ABSTRACT

A mold is used to form a solder joint to join the distal end of the guidewire to a wire coil. The mold has a cavity that can have different configurations so that the solder joint can be any of bullet shaped, micro-J shaped, cone shaped, truncated cone shaped, or have a textured surface.

BACKGROUND

This invention relates to the field of guidewires for advancingintraluminal devices such as stent delivery catheters, balloondilatation catheters, atherectomy catheters and the like within bodylumens.

In a typical coronary procedure a guiding catheter having a preformeddistal tip is percutaneously introduced into a patient's peripheralartery, e.g., femoral or brachial artery, by means of a conventionalSeldinger technique and advanced therein until the distal tip of theguiding catheter is seated in the ostium of a desired coronary artery.There are two basic techniques for advancing a guidewire into thedesired location within the patient's coronary anatomy, the first is apreload technique which is used primarily for over-the-wire (OTW)devices and the second is a bare wire technique which is used primarilyfor rapid exchange type systems. With the preload technique, a guidewireis positioned within an inner lumen of an OTW device such as adilatation catheter or stent delivery catheter with the distal tip ofthe guidewire just proximal to the distal tip of the catheter and thenboth are advanced through the guiding catheter to the distal endthereof. The guidewire is first advanced out of the distal end of theguiding catheter into the patient's coronary vasculature until thedistal end of the guidewire crosses the arterial location where theinterventional procedure is to be performed, e.g., a lesion to bedilated or a dilated region where a stent is to be deployed. Thecatheter, which is slidably mounted onto the guidewire, is advanced outof the guiding catheter into the patient's coronary anatomy over thepreviously introduced guidewire until the operative portion of theintravascular device, e.g., the balloon of a dilatation or a stentdelivery catheter, is properly positioned across the arterial location.Once the catheter is in position with the operative means located withinthe desired arterial location, the interventional procedure isperformed. The catheter can then be removed from the patient over theguidewire. Usually, the guidewire is left in place for a period of timeafter the procedure is completed to ensure reaccess to the arteriallocation. For example, in the event of arterial blockage due todissected lining collapse, a rapid exchange type perfusion ballooncatheter can be advanced over the in-place guidewire so that the ballooncan be inflated to open up the arterial passageway and allow blood toperfuse through the distal section of the catheter to a distal locationuntil the dissection is reattached to the arterial wall by naturalhealing.

With the bare wire technique, the guidewire is first advanced by itselfthrough the guiding catheter until the distal tip of the guidewireextends beyond the arterial location where the procedure is to beperformed. Then a rapid exchange (RX) catheter is mounted onto theproximal portion of the guidewire which extends out of the proximal endof the guiding catheter, which is outside of the patient. The catheteris advanced over the guidewire, while the position of the guidewire isfixed, until the operative means on the RX catheter is disposed withinthe arterial location where the procedure is to be performed. After theprocedure, the intravascular device may be withdrawn from the patientover the guidewire or the guidewire advanced further within the coronaryanatomy for an additional procedure.

Conventional guidewires for angioplasty, stent delivery, atherectomy andother vascular procedures usually comprise an elongated core member withone or more tapered sections near the distal end thereof and a flexiblebody such as a helical coil or a tubular body of polymeric materialdisposed about the distal portion of the core member. A shapeablemember, which may be the distal extremity of the core member or aseparate shaping ribbon, which is secured to the distal extremity of thecore member, extends through the flexible body and is secured to thedistal end of the flexible body by soldering, brazing or welding whichforms a rounded distal tip. Torqueing means are provided on the proximalend of the core member to rotate, and thereby steer, the guidewire whileit is being advanced through a patient's vascular system.

For certain procedures, such as when delivering stents around achallenging take-off, e.g., a shepherd's crook, tortuosities or severeangulation, substantially more support and/or vessel straightening isfrequently needed from the guidewire than normal guidewires can provide.Guidewires have been commercially introduced for such procedures whichprovide improved distal support over conventional guidewires, but suchguidewires are not very steerable and in some instances are so stiffthat they can damage vessel linings when advanced therethrough. What hasbeen needed and heretofore unavailable is a guidewire which provides ahigh level of distal support with acceptable steerability and littlerisk of damage when advanced through a patient's vasculature.

In addition, conventional guidewires using tapered distal core sectionsas discussed above can be difficult to use in many clinicalcircumstances because they have an abrupt stiffness change along thelength of the guidewire, particularly where the tapered portion beginsand ends. As a guidewire having a core with an abrupt change instiffness is moved through tortuous vasculature of a patient, thephysician moving the guidewire can feel the abrupt resistance as thestiffness change is deflected by the curvature of the patient'svasculature. The abrupt change in resistance felt by the physician canhinder the physician's ability to safely and controllably advance theguidewire through the vasculature. What has been needed is a guidewirethat does not have an abrupt change in stiffness, particularly in theportions of the distal section that are subject to bending in thevasculature and guiding catheter. The present invention satisfies theseand other needs by providing distal tip integrity, kink resistance,enhanced torque response, improved distal tip radiopacity, and a smoothtransition region.

SUMMARY OF THE INVENTION

In one embodiment of the invention a guidewire has a radiopaque innercoil and a substantially non-radiopaque outer coil. The inner coil andthe outer coil are attached to the distal end of the guidewire and theouter coil covers the inner coil and extends proximally along theguidewire proximal of a proximal end of the inner coil. The inner coilis formed from a radiopaque material so that the physician can easilydetect the location of the distal end of the guidewire under fluoroscopyduring a procedure. Both the inner coil and the outer coil can be formedfrom a single strand of wire or a multifilar strand of wire.

In another embodiment, a mold is used for forming a solder distal tip orsolder joint at the distal end of the guidewire. The solder distal tipattaches the distal end of the guidewire and the distal end of the innercoil and the distal end of the outer coil (if present) together. It isimportant that the solder distal tip be uniform from one guidewire tothe next, and repeatable in structural formation. A mold, including asplit mold, provides a bullet shaped solder tip or a micro-J shape tipat the distal end of the guidewire to attach the inner and outer coilsto the guidewire. Other shapes of solder tips are contemplated such ascone shape, truncated cone shape, and a solder joint having a texturedsurface.

In another embodiment, a laser is used to form dimples on the solderjoint connecting the distal end of the guidewire. A laser is used toform dimples on the distal end of the solder joint such that the dimplesresemble the dimples on a golf ball and can have specific spacing andpatterns. The laser can be programmed to provide dimples that are spacedapart and have specific diameters and depths depending on therequirements of the user.

In another embodiment, the present invention guidewire increases thetorqueability of the guidewire without negatively affecting the bendingstiffness and functionality of the guidewire by using differentcross-section shapes of the coils. For example, the differentcross-section shapes of the coils can include I-beam, verticalrectangular, vertical ellipse, square, peanut shape, vertical hexagonal,horizontal hexagonal, and horizontal ellipse cross-sections. Consideringthe constraints due to manufacturing, dimensions, and tolerances, theI-beam, peanut shape, vertical rectangular and vertical ellipse shapedcross-sections are more favorable than a conventional roundcross-section coil, for increasing torquability without negativelyaffecting the bending stiffness of the guidewire. The differentcross-section shaped coils can be used to form a single wire coil or amultifilar coil.

In another embodiment a guidewire tip shaping tool forms a micro-J shapein the distal tip of the guidewire. The shaping tool is provided to thephysician with the guidewire so that the physician can select the amountof bend in the distal end of the guidewire using the shaping tool.Traditionally, the physician would bend the distal end of the guidewirewith his/her hands, which lacked control of the bend angle and shape ofthe bend. The shaping tool includes a number of cavities having adifferent angular orientation and depth so that the physician can selectthe length of the bend and the angle of the bend in the distal tip ofthe guidewire. The shaping tool is spring loaded toward the openposition so that the guidewire distal end can be inserted into a cavity.Once the guidewire is inserted into a cavity, the physician gentlypresses the ends of the shaping tool to overcome the spring force andshift an inner tube having the cavity relative to an outer tube to formthe bend in the distal tip of the guidewire. The predetermined angle andlength of the cavities provide a consistent micro-J shape for thephysician to use.

In another embodiment of the invention, the distal section of theguidewire is reduced in cross-section to be more flexible whennavigating tortious vessels. In this embodiment, a parabolic distalsection of the guidewire includes a significant portion of the distalsection having been ground down to form a continuous taper. Thecontinuous taper is formed by a parabolic grind along the distal sectionof the guidewire. The parabolic grind provides a smooth curvilineartransition along the distal section of the guidewire that is highlyflexible and yet maintains a linear change in stiffness therebyproviding excellent torque and tactical feedback to the physician whenadvancing the guidewire through tortuous anatomy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a prior art guidewire depicting a coilat the distal end of the guidewire.

FIG. 2 is an elevational view of a guidewire of the invention depictingan inner coil and an outer coil at the distal end of the guidewire.

FIG. 3 is an elevational view of a multifilar guidewire for use as aninner coil or an outer coil on a guidewire.

FIG. 4A is an elevational view of an eight filar strand coil for use asan inner or outer coil on the distal end of the guidewire.

FIG. 4B is a longitudinal cross-sectional view of the eight filar strandcoil of FIG. 4A.

FIG. 5 is a chart depicting the torque analysis for guidewires of theinvention having different filar strand coils.

FIG. 6 is a graph depicting the guidewires shown in FIG. 5 and showingthe radiopacity of the distal portion of the guidewires including thecoils.

FIG. 7A is an elevational view of a mold for forming a solder joint onthe distal end of a guidewire.

FIG. 7B is a cross-sectional view taken along lines 7B-7B of the mold ofFIG. 7A.

FIG. 8A is an elevational view of a mold for forming a solder joint onthe distal end of a guidewire.

FIG. 8B is an elevational view of the split mold of FIG. 8A.

FIG. 9A is a cross-sectional view of a mold used for forming a solderjoint at the distal end of a guidewire and depicting the cavity forreceiving a molten metal.

FIG. 9B is a top view of the solder joint formed by the mold of FIG. 9A.

FIG. 9C is an elevational view of the solder joint formed by the mold ofFIG. 9A.

FIG. 10A is an elevational view of a mold for forming a solder jointhaving a micro-J shape.

FIG. 10B is an elevational view of a mold for forming a solder jointhaving a micro-J shape.

FIG. 11A is a top view of a joint depicting a series of dimples formedby a laser.

FIG. 11B is an elevational view of the joint of FIG. 11A.

FIG. 12A is a top view of a joint depicting a series of dimples formedby laser.

FIG. 12B is an elevational view of the joint of FIG. 12A.

FIG. 12C is an enlarged top view of the joint of FIG. 12A.

FIG. 12D is a side view depicting one dimple formed in the jointdepicted in FIG. 12C.

FIG. 12E is a chart depicting test data comparing the time to passthrough a lesion for the laser dimpled guidewire compared to acommercially available guidewire.

FIG. 13 is an elevational view of a prior art coil having a circular orround cross-section wire.

FIG. 14 is a chart depicting the elastic modulus, yield strength, andultimate strength of 304V stainless steel.

FIGS. 15A and 15B are elevational and front views of a prior art coilhaving a circular or round cross-section.

FIGS. 16A and 16B are elevational and front views respectively, of acoil having an I-beam cross-section.

FIGS. 17A and 17B are elevational and front views respectively, of acoil having a vertical rectangular cross-section.

FIGS. 18A and 18B are elevational and front views respectively, of acoil having a vertical ellipse cross-section.

FIGS. 19A and 19B are elevational and front views respectively, of acoil having a square cross-section.

FIGS. 20A and 20B are elevational and front views respectively, of acoil having a vertical hexagonal configuration.

FIGS. 21A and 21B are elevational and front views respectively, of acoil having a horizontal hexagonal cross-section.

FIGS. 22A and 22B are elevational and front views respectively, of acoil having a flat cross-section.

FIGS. 23A and 23B are elevational and front views respectively, of acoil having a horizontal elliptical cross-section.

FIG. 24 depicts the torque response of single wire coils havingdifferent cross-sections shown in FIGS. 15A-23B.

FIG. 25 is a chart showing the bending stiffness of the coils havingdifferent cross-sections as depicted in FIGS. 15A-23B.

FIG. 26 is an elevational view of a distal end of a guidewire insertedinto a fixture depicting the angular shape of the micro-J bend in thedistal tip of the guidewire.

FIG. 27A is an exploded perspective view of a shaping tool for forming amicro-J bend in the distal end of a guidewire.

FIG. 27B is an elevational perspective view of a shaping tool forforming a micro-J bend in the distal end of a guidewire.

FIG. 28A is an elevational view of a shaping tool in an open positionfor forming a micro-J bend in the distal end of a guidewire.

FIG. 28B is an elevational view of a shaping tool in a closed positionforming a micro-J bend in the distal end of the guidewire.

FIG. 29 is an enlarged circular view taken along lines 29-29 depicting achannel and a cavity for receiving the distal end of a guidewire.

FIG. 30 is an enlarged circular view of the cavity of FIG. 29 in which aguidewire has been inserted through the channel and in to the cavity andis being bent into a micro-J shape.

FIG. 31 is an elevational view of a prior art guidewire depicting adistal section having multiple tapered sections.

FIG. 32 is an elevational view of a guidewire depicting a distal sectionhaving a parabolic grind profile.

FIG. 33 is a graph depicting the bending stiffness along the distalsection of the guidewires shown in FIGS. 31 and 32.

FIG. 34 is a schematic depicting the tapered distal section of a priorart guidewire kinking in a side branch vessel.

FIG. 35 is a graph of a 0.014 inch diameter guidewire depicting a distalsection having a parabolic grind profile.

FIG. 36 is a graph of a 0.014 inch diameter guidewire depicting a distalsection having a parabolic grind profile.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior Art Guidewires

Prior art guidewires typically include an elongated core wire having aflexible atraumatic distal end. A prior art guidewire is shown in FIG. 1and includes an elongated core member 11 with a proximal core section12, a distal core section 13, and a flexible body member 14 which isfixed to the distal core section. The distal core section 13 has atapered segment 15, a flexible segment 16 which is distally contiguousto the tapered segment 15, a distal end 13 a, and a proximal end 13 b.The distal section 13 may also have more than one tapered segment 15which have typical distally decreasing tapers with substantially roundtransverse cross sections.

The core member 11 may be formed of stainless steel, NiTi alloys orcombinations thereof. The core member 11 is optionally coated with alubricious coating such as a fluoropolymer, e.g., TEFLON® available fromDuPont, which extends the length of the proximal core section.Hydrophilic coatings may also be employed. The length and diameter ofprior art guidewire 10 may be varied to suit the particular proceduresin which it is to be used and the materials from which it isconstructed. The length of the guidewire 10 generally ranges from about65 cm to about 320 cm, more typically ranging from about 160 cm to about200 cm, and preferably from about 175 cm to about 190 cm for thecoronary anatomy. The guidewire diameter generally ranges from about0.008 inch to about 0.035 inch (0.203 to 0.889 mm), more typicallyranging from about 0.012 inch to about 0.018 inch (0.305 to 0.547 mm),and preferably about 0.014 inch (0.336 mm) for coronary anatomy.

The flexible segment 16 terminates in a distal end 18. Flexible bodymember 14, preferably a coil, surrounds a portion of the distal sectionof the elongated core 13, with a distal end 19 of the flexible bodymember 14 secured to the distal end 18 of the flexible segment 16 by thebody of solder 20. The proximal end 22 of the flexible body member 14 issimilarly bonded or secured to the distal core section 13 by a body ofsolder 23. Materials and structures other than solder may be used tojoin the flexible body 14 to the distal core section 13, and the term“solder body” includes other materials such as braze, epoxy, polymeradhesives, including cyanoacrylates and the like.

The wire from which the flexible body 14 is made generally has atransverse diameter of about 0.001 to about 0.004 inch, preferably about0.002 to about 0.003 inch (0.05 mm). Multiple turns of the distalportion of the coil may be expanded to provide additional flexibility.The coil may have a diameter or transverse dimension that is about thesame as the proximal core section 12. The flexible body member 14 mayhave a length of about 2 to about 40 cm or more, preferably about 2 toabout 10 cm in length. A flexible body member 14 in the form of a coilmay be formed of a suitable radiopaque material such as platinum oralloys thereof or formed of other material such as stainless steel andcoated with a radiopaque material such as gold.

The flexible segment 16 has a length typically ranging about 1 to about12 cm, preferably about 2 to about 10 cm, although longer segments maybe used. The form of taper of the flexible segment 16 provides acontrolled longitudinal variation and transition in flexibility (ordegree of stiffness) of the core segment. The flexible segment iscontiguous with the core member 11 and is distally disposed on thedistal section 13 so as to serve as a shapable member.

Guidewire Having Radiopaque Inner Coil

In keeping with the invention, in one embodiment shown in FIGS. 2-6, aguidewire 30 has an elongated core member 32 with a proximal coresection 34 and a distal core section 36. The distal core section 36 ispreferably tapered, having a tapered segment 38 that tapers to a smallerdiameter moving from the proximal end 40 of the guidewire toward thedistal end 42 of the guidewire. The elongated core member 32 ispreferably formed from stainless steel, however, it also can be formedfrom other metals or metallic alloys known in the art.

In order to improve radiopacity, the guidewire 30 shown in FIGS. 2-6includes a radiopaque inner coil 44 positioned over the elongated coremember at the distal end 42 thereof. The inner coil 44 may be 3 cm inlength and have a distal end 46 that is coterminous with the distal end42 of the elongated core member 32. While 3 cm is a preferred length forthe radiopaque inner coil 44, the length of the inner coil 44 can rangefrom 0.5 cm to 15 cm as necessary to satisfy the needs of the physician.The radiopaque inner coil 44 has a proximal end 48 with multiple coils50 extending from the proximal end 48 to the distal end 46. Theradiopaque inner coil 44 is made from a radiopaque material taken fromthe group of radiopaque metals including platinum (Pt), palladium (Pd),iridium (Ir), tungsten (W), tantalum (Ta), rhenium (Re) and gold (Au).In one embodiment, shown in FIG. 2, the radiopaque inner coil 44 isformed from a single filar coil 50 of wire, and the diameter can vary asrequired for a balance in radiopacity, flexibility, torquability andkink resistance (durability). In another embodiment, shown in FIG. 3,the radiopaque inner coil 44 is formed from a four filar coil 52 ofwire. The four filar coil 52 can be made with drawn, filled tubing (tubefilled radiopaque material or sandwiched) which is known in the priorart. The inner coil 44 can be formed using any number of filars, such asthe eight filar coil shown in FIGS. 4A and 4B. In one embodiment, theeight filar coil of FIGS. 4A and 4B is 31 cm long, has an outer diameterof 0.0135±0.0005 inch, an inner diameter of 0.0095 inch, a pitch of0.193 inch, a wire diameter of 0.002 inch, and a spacing between theeight filar segments of 25% of the wire diameter. These dimensions arerepresentative and can vary depending upon different needs. Importantly,all of the various coil shapes can be formed of the radiopaque metalslisted herein so that the radiopaque inner coil 44 is radiopaque andeasily seen by the physician under fluoroscopy.

The embodiment in FIGS. 2-6 also includes a non-radiopaque outer coil 56that has an inner diameter 58 that is greater than an outer diameter 60of the radiopaque inner coil 44 and greater than the outer diameter ofthe elongated core member 32. The non-radiopaque outer coil 56 is formedfrom a non-radiopaque material including stainless steel (SS),cobalt-chromium (CoCr), and nickel-titanium (NiTi) alloys. Thenon-radiopaque outer coil can range in length from 10 cm to 60 cm from adistal end 62 to a proximal end 64. In one embodiment, thenon-radiopaque outer coil 56 is 30 cm long.

As shown most clearly in FIG. 2, the distal end 46 of the radiopaqueinner coil 44, the distal end 42 of the guidewire 30, and the distal end62 of the non-radiopaque outer coil 56 all are connected together bysolder, glue, weld or braze. Preferably, a solder ball 66 is formed atthe distal end 42 of the guidewire 30 in a known manner to connect theradiopaque inner coil 44 to the non-radiopaque outer coil 56 and to theguidewire distal end 42. It is important to emphasize that the distalend 46 of the radiopaque inner coil 44 preferably does not contact thedistal end 62 of the non-radiopaque outer coil 56, they are connectedtogether by the solder ball 66, but after the solder ball 66 is formed,there may be direct contact with each other. The distal end 46 of theradiopaque inner coil 44 does contact the distal end 42 of the elongatedcore member 32. The proximal end 48 of the radiopaque inner coil 44 isconnected to the elongated core member 32 by first solder joint 70,weld, glue, or braze, in a known manner. The proximal end 48 of theradiopaque inner coil 44 is not attached to the non-radiopaque outercoil 56. The proximal end 64 of the non-radiopaque outer coil 56 isattached to the elongated core member 32 by second solder joint 72,weld, glue, or braze, in a known manner. The first solder joint 70 isproximal of the solder ball 66 and distal of the second solder joint 72.The proximal end 64 of the non-radiopaque outer coil 56 is not connectedto any portion of the radiopaque inner coil 44, thereby providing aseamless outer surface 68 along non-radiopaque outer coil 56 with nosolder joint with the radiopaque inner coil to create a stiffnessproblem. Preferably, as shown in FIG. 2, there is a gap between theelongated core member 32 and the inner coil 44 and the outer coil 56,and a gap between the inner coil 44 and the outer coil 56 Like theradiopaque inner coil 44, the non-radiopaque outer coil 56 can be formedfrom the single filar coil 50, a four filar coil 56 (FIG. 3), or anynumber of filar coils such as the eight filar coil shown in FIGS. 4A and4B.

As shown in the graph in FIG. 5, experiments were conducted to determinethe effects of multifilar coils on torque. In FIG. 5, the StraightTorque was measured for a guidewire having an inner and outer coil withonly one filar, a guidewire having an inner and outer coil with fourfilars, six filars, eight filars, and an inner and outer coil that islaser cut in the form of a vertical rectangle. As can be seen in FIG. 5,the single filar coils and multifilar coils of the invention comparefavorably in torque performance.

Testing also was conducted on guidewires of the invention to measureradiopacity, as seen in FIG. 6. The guidewires in Groups 1-6 have aradiopaque inner coil and a non-radiopaque outer coil, as disclosed inFIG. 2. The radiopacity of the radiopaque inner coil compares favorablyunder fluoroscopy compared to the commercially available WHISPER®guidewire sold by Abbott Cardiovascular Systems, Santa Clara, Calif.

In one embodiment, shown in FIG. 2, a proximal section 74 of theguidewire 30 has a silicone based hydrophobic coating and apolytetrafluoroethylene coating (PTFE). A distal section 76 has apolyvinylpyrrolidone hydrocoat coating (PVP). Typically, the distal end42 of the guidewire 30 is uncoated.

Mold For Forming Solder Distal Tip

Guidewires are available in many different configurations including tipload, support profile, and materials of construction, all selected by aphysician for specific clinical case requirements. For certainsituations it has been perceived that a guidewire distal tip with aspecific geometry provides the physician a mechanical advantage innavigating a tortuous path or occluded segment. In this embodiment, thecharacteristics of molten solder flow is overcome to contain the moltensolder flow within a predetermined shape. Currently, a solder joint isformed at the distal tip of the guidewire attaching the elongated corewire to the outer coils. This solder joint is formed utilizing aconventional soldering iron to heat and flow the solder onto the corewire and secure the coils to the core wire when solidified. The presentinvention creates a soldered tip by a different means, and allows aspecific shape to be achieved by casting the molten solder in apredetermined shape.

As shown in FIGS. 7A-10B, a mold 80 is used to cast the soldered tip,which overcomes many obstacles both in cost and manufacturability. Usingthe mold 80 to form a predetermined soldered shape provides not only theintended geometry of the solder joint, but also performs the necessarysolder bond attaching the guidewire elongated core wire to the outercoils (see FIGS. 2-6 for example). The mold could be machined as simpleas a bullet shaped tip 82 or it could be machined to include a smallangular feature to what is referred to as a micro-J shaped tip 84.Utilizing mold 80 to perform this solder tip operation allows theengineering team the ability to change the configuration to suit therequirements for the product being produced.

The mold 80 is made as a solid mold constructed of ceramic or othersuitable material able to withstand the temperature required to receivemolten solder. The mold 80 has a cavity 86 which receives the moltensolder and the distal tip of the guidewire elongated core wire, and thedistal end of any coils, if present. The shape of the cavity 86determines the shape of the solder joint, such as the bullet shaped tip82 and the micro-J shaped tip 84.

A more complex shape is achieved by utilizing a split mold 90 where afirst shell 92 and a second shell 94 are held together while the solderis molten, and then separated to release the solder tip 88. The splitmold 90 has the solder tip 88 configuration machined into a first face96 and the mirror image machined into a second face 98. The split mold90 can be machined as the bullet shaped tip 82 or to include a smallangular feature to form the micro-J shaped tip 84. Various other soldertip 88 shapes can be formed by the spilt mold 90 such as cone shaped,truncated cone shaped, and a textured surface.

The method to form the solder tip 88 includes placing the molds into aheating apparatus and allowing the solder to become molten. Once molten,the distal tip of a guidewire elongated core wire is submerged into themold cavity 86 allowing solder to flow onto the distal tip and the firstfew winds of the outer coil (if present). A thermally conductivematerial can be placed around segments of the outer coil, just above themold cavity 86, to prevent solder from flowing to undesirable places andcontrol the precise placement of the solder tip 88. Once the solder hasflowed to the specified area, the split mold 90 is rapidly cooledallowing the solder to solidify and bond the guidewire distal tip andcoils together. Once cooled, the part may be withdrawn from mold 80, orthe first and second shells 92, 94 are separated, and the solder tip 88can be removed.

Utilizing mold 80 to form the solder tip 88 allows the engineering teamthe ability to quickly change the configuration for the product beingproduced.

Additionally, the first face 96 and the second face 98 can be modifiedto provide some type of feature or texture depending on the needs of thespecific product driven by the application. The mold 80 may possess someform of texture or even have grooves, either raised or recessed, toallow a specific outer surface geometry as required for specifiedproduct requirements. For example, as shown in FIGS. 9A-9C, split mold90 has angular grooves 100 formed in the mold cavity 86 so that thesolder tip 88 has matching angular grooves 102.

While the vast majority of guidewires will use solder to form the bondat the distal tip and connect the coils, some guidewires may use epoxyor another similar material instead of solder. The foregoing descriptionrelating to FIGS. 7A-10B relating to the solder tip 88 applies as wellto other suitable metals and epoxy.

Laser To Form Dimpled Joint

Generally, most commercially available guidewires have guidewire tipsmade from solder material or weld material and have a smooth,dome-shaped surface. Such guidewires encounter challenges when used tocross calcified and fibrous tissues, to treat chronic total occlusions(CTO). Certain commercially available guidewires are designed to havehigher tip loads in order to treat CTO and penetrate through complex andstenosed lesions. Optimal wire strength, tip load and tip shape helpwith push-ability and maneuvering the guidewire through the lesions,however, with a smooth tip surface likely will have challenges engagingcalcified and fibrous tissues resulting tip deflection and failure topenetrate through the lesion. In one embodiment, shown in FIGS. 11A-12D,a laser (not shown) is used to form a textured or roughened surface 154on the solder/weld joint 156 at the distal tip of the guidewire 150.Commercial lasers, such as a fiber laser, are capable of a focused spotof approximately 0.001 inch, and can provide random or tightly stitchedpatterns as shown in FIGS. 11A and 11B, or provide spaced apart dimples158 as shown in FIGS. 12A-12C. The dimples 158 resemble the dimples on agolf ball and can have specific spacing and patterns. In one embodiment,the laser creates a series of dimples 158 that have a diameter of 0.001inch and are spaced apart 0.001 inch. In another embodiment, the dimples158 have a diameter in the range from 0.0005 inch to 0.005 inch and havespacing between dimples 158 in the range from 0.0005 inch to 0.005 inch.In another embodiment, the laser creates dimples 158 having a diameterof 0.001 inch and spaced apart by 0.0005 inch, which forms the texturedsurface 154. It is also possible to provide greater spacing between thedimples 158 to provide a mechanical advantage in specific clinicalcases. The laser can be programmed to provide areas on the solder/weldjoint 156 that are left untouched (i.e., smooth), depending on theapplication. The ablated patterns (dimples 158) are easily modified bysimply altering the laser frequency, grid spacing (spaced apart dimples158), or programming dimple by dimple to achieve an optimalconfiguration.

The dimples 158 also have a depth dimension 160 and a diameter 162 asshown in FIG. 12D. Preferably, the dimples 158 have a depth dimension160 ranging from 0.5μ to 1.5μ, and more preferably 1.0 μ.

Similarly, the radius dimension 162 of dimples 158 can range from 0.3μto 6.0μ, and preferably from 2.0μ to 4.0μ, and more preferably 3.0μ. Theprocess involves utilizing a commercially available fiber laser, withthe wire tip fixture end on, to selectively soften and dimple thesolder/weld surface of the guidewire tip where the beam is directed.This process is performed without disrupting the solder/weld structuralintegrity of the solder or weld material due to the extremely fast pulserate of the laser providing focused heating only where the beam istargeted. In one embodiment, the cycle time for the laser process is 50ms, which allows for a modified tip texture in a time that is acceptablein a production environment. Higher or lower laser cycle times areacceptable depending on the composition of the solder/weld and the sizeand depth of the dimples.

In addition to using a commercially available laser, the dimples 158 canbe formed by other processes including bead blasting, chemical etching,or mechanical impact, as long as the integrity of the solder/weld joint156 is maintained.

The dimples 158 can be formed on the solder/weld joint 156 after thejoint has been formed on the distal tip 152 of the guidewire 150.Alternatively, the solder/weld joint 156 is manufactured at a componentlevel and the dimples 158 are then formed on the joint. Thereafter, thesolder/weld joint 156 with the pre-formed dimples 158 can be attached tothe distal tip 152 of the guidewire 150.

As shown in FIG. 12E, an experiment was conducted comparing lesioncrossing performance of the laser dimpled guidewire with commerciallyavailable guidewires. Testing was performed on a clinically relevantChronic Total Occlusion (CTO) model to determine the time to pass theguidewire through the lesion. The round dots represent the time inseconds it took the guidewire to pass through the lesion, while thetriangular dots represent those guidewires that were unable to passthrough the lesion. As can be seen in FIG. 12E, the laser dimpledguidewire performed substantially better than a commercially availableguidewire and a wire with no dimples in terms of consistently betterpassing times, and no failed attempts to pass through the lesion.

Coils With Different Cross Section Shapes

Generally, the distal end of a guidewire should have a low supportprofile to make it flexible enough for cross-ability purposes.Therefore, the distal end of the core wire is ground (tapered) andcovered with a coil to make it flexible and atraumatic (see e.g., FIGS.2-3). Also, the coil will assist with keeping the outer diameter of theguidewire consistent. Prior art coils are formed from a wire with acircular cross section (FIG. 13) and cut with a laser.

For the next generation guidewires, good torque response withoutnegatively affecting the bending stiffness of the guidewire is animportant functional attribute.

In the present invention, multiple wire cross-sections were designed toimprove the functionality of the guidewires. Finite Element Analysis(FEA using ABAQUS commercial software) was performed on these guidewirecross sections to identify the effect of different cross-sections ontorque response and bending stiffness.

The present invention increases the torquability without negativelyaffecting the bending stiffness and functionality of guidewire usingdifferent cross-section shapes of coils. As shown in FIGS. 15A-23B, thedifferent embodiments include circle 178 (prior art), I-beam 180,vertical rectangular 182, vertical ellipse 183, square 184, verticalhexagonal 186, horizontal hexagonal 188, flat 190, and horizontalellipse 192 cross-sections. FEA demonstrates that the more materialremoved away from the Neutral Axis (N. A.) of the coil wire, increasesthe torquability while decreasing the bending stiffness. Coils withdifferent cross-sections were created and subjected to torque whilekeeping the other parameters such as material and volume of the coilwires constant. For this study, the coil material considered was 304Vstainless steel. FIG. 14 shows the material properties for 304Vstainless steel. In order to keep the volume constant, thecross-sectional area, the length, the nominal diameter, and the pitchfor the wires were kept constant.

Coils having different cross sections with the same length, pitch, meandiameter and cross-sectional area (dimensions scaled up to 100) areshown in FIGS. 15A-23B. FIG. 24 shows the torque response of singlecoils with different cross-sections analyzed by ABAQUS using theprovided material properties. The torsional stiffness of the I-beam isthe highest followed by the rectangular and vertical ellipsecross-sections. A peanut shaped cross-section wire also showed hightorsional stiffness (FIG. 24). FIG. 25 shows the bending stiffness ofthe coils with different cross-sections. Therefore, by changing thecross-section of the wire of a coil from circular to I-beam, the torqueresponse increased up to 250% while decreasing the bending stiffness by50%. Considering the constraints due to manufacturing, dimensions andtolerances the I-beam, peanut, vertical rectangular and vertical ellipseshapes are more favorable than the conventional round cross-sectioncoils, depending on the application or other limitations.

In FIGS. 15A-23B, the shapes and sizes related to the coils 178, 180,182, 183, 184, 186, 188, 190 and 192 are for illustrative purposes andto ensure the parameters such as length, pitch, mean diameter andcross-sectional area of the coil wires were constant for testingpurposes.

The coils 180, 182, 183, 184, 186, 188, 190 and 192 can be used with theguidewire 30 shown in FIGS. 2-6 and can be used as either an inner coilor an outer coil.

Guidewire Tip Shaping Tool—Micro J

Guidewires are sold either in a straight or pre-formed “J” shapedconfiguration. Generally, the distal tip of the guidewires are micro “J”shaped to assist with maneuverability. Wires can be shaped by themanufacturer or by the physician using a shaping tool provided with theguidewire. Shaping by the manufacturer is an automated process, which ismore repeatable and does not compromise the integrity of the wire. Themajority of users prefer a straight wire and shape the tips themselves.Guidewire manufactures provide a mandrel and introducer to assistphysicians with the wire shaping.

It has been determined that users do not have good control in how theyshape the wire and can easily damage the wire. Testing shows that thereis an optimal angle (i.e., ˜20°-30°) and distance from the tip (2-3 mm)that can significantly help with the wire performance. Even thoughphysicians know what specifications they want in the bend, due to thesize, most of the physicians are nowhere close to the intended optimaldimensions. Also, there is a higher risk of the wire losing integrityand functional performance if the physician performs the shaping.

In this embodiment, shown in FIGS. 26-30, a micro “J” shaping tool canbe shipped with the guidewires or can be sold as a standalone accessory.This shaping tool will have pre-defined existing slots where a physiciancan decide the angle as well as the distance from the tip to form themicro-J bend. This tool has a universal design and will be compatiblewith all manufacturers guidewires as well.

In this embodiment, shown in FIGS. 27A-30, a shaping tool 200 includes afirst member 202 and a second member 204, and multiple cavities 206having different depths and shapes. A channel 208 extends through a wall210 of the first member 202 and provides access for the distal end 212of the guidewire 214. The second member 204 is slidably contained in thefirst member 202 and a third member 205 is inserted into a slot 207 inthe first member 202 to hold the second member 204 in the first member204. The third member 205 can be glued or laser welded in the slot 207,but it allows for longitudinal movement or sliding between the firstmember 202 and the second member 204. A pair of springs 216 are springbiased to keep the spacing tool 200 in an open position 218. In the openposition 218, the distal end 212 of the guidewire 214 can be insertedthrough channel 208 and advanced into one of the cavities 206 (see FIG.27B). To form the micro-J tip, the user pushes the end of the secondmember 204 in the direction of the arrow in FIGS. 28A and 28B, whichovercomers the spring force of springs 216. As shown in FIGS. 28A-30,the second member 204 slides relative to the first member 202 to closedposition 220. In the closed position 220, the cavities 206 have shiftedrelative to the channels 208 so that the guidewire distal end 212 willbend the predetermined angle and the bend will be set at a predeterminedlength from an end 222 of the distal end 212. When the user releasespressure on the end of the shaping tool 200, the springs 216 spring openand move the first member 202 to the open position 218 so that theguidewire 214 can be removed from the cavity 206. While the cavities 206depict angular bends of 25° and 30°, a range of angular bends from 5° to40° is contemplated. Similarly, the length of the bend from the distalend 220 to the unbent portion of the guidewire 214 is preferably 1 mm or2 mm, however, the length can range from 0.5 mm to 5 mm.

Parabolic Grind Profile

In another embodiment of the invention, the distal section of theguidewire is reduced in cross-section to be more flexible whennavigating tortuous vessels, such as coronary arteries. The distalsection of the guidewire must be both flexible and pushable, that is thedistal section must flex and be steerable through the tortuous arteries,and also have some stiffness so that it can be pushed or advancedthrough the arteries without bending or kinking. A prior art guidewireis shown in FIG. 31 and has a distal section comprised of taperedsections and core sections with no taper. The resulting bendingstiffness is shown in the graph in FIG. 33 wherein the bending stiffnessdecreases at each tapered position, and the bending stiffness remainsconstant along the core section that is not tapered. The tapered distalsection of the prior art guidewire of FIG. 31 provides abrupt changes inbending stiffness that can reduce the tactile feel to the physician whenadvancing the guidewire through tortuous anatomy. In fact, in some priorart guidewires, the abrupt change in bending stiffness can result in thedistal tip of the guidewire to kink or prolapse into a side branchvessel as shown schematically in FIG. 34. Prolapse can be dangerous tothe patient in that the artery can be damaged or punctured. Importantly,it is preferred to maintain the outer diameter of the core section asfar distal as possible to maintain torque. Each tapered section losestorque, which is critical in advancing the guidewire through tortuousvessels.

In keeping with the invention, a parabolic distal section 232 of aguidewire 230 is shown in FIG. 32 wherein a significant portion of thedistal section has been ground to form a continuous taper. Morespecifically, the continuous taper is formed by a parabolic grind alongparabolic distal section 232 of the guidewire 230. The parabolic grindprovides a smooth curvilinear transition along section 232 that ishighly flexible and yet maintains a linear change in stiffness as shownin the graph of FIG. 33. Not only is parabolic distal section 232flexible, but it has a linear change in stiffness thereby providingexcellent torque and tactile feedback to the physician when advancingthe guidewire through tortuous anatomy. A tapered section 234 that isnot curvilinear (not a parabolic grind section) is located on theguidewire 230 distal of the parabolic distal section 232 and it providesreduced bending stiffness and a linear change in bending stiffness asshown in the graph of FIG. 33.

Bending stiffness can be measured in a variety of ways. Typical methodsof measuring bending stiffness include extending a portion of the sampleto be tested from a fixed block with the sample immovably secured to thefixed block and measuring the amount of force necessary to deflect theend of the sample that is away from the fixed block a predetermineddistance. A similar approach can be used by fixing two points along thelength of a sample and measuring the force required to deflect themiddle of the sample a fixed amount. Those skilled in the art willrealize that a large number of variations on these basic methods existincluding measuring the amount of deflection that results from a fixedamount of force on the free end of a sample, and the like. Other methodsof measuring bending stiffness may produce values in different units ofdifferent overall magnitude, however, it is believed that the overallshape of the graph will remain the same regardless of the method used tomeasure bending stiffness.

The parabolic grind profiles for a 0.014 inch diameter guidewire areshown in FIGS. 35 and 36 respectively. The guidewire in FIG. 35 has an11 gram tip load and the guidewire in FIG. 36 has a 14 gram tip load.The unit of measure on the Y-axis is in inches and the X-axis is incentimeters. In both FIGS. 35 and 36, two parabolic grind profiles areseparated by a uniform diameter core wire segment. More specifically,each graph shows a first parabolic grind profile starting atapproximately 23.1 cm from the distal tip of the guidewire and ending atapproximately 17.9 cm from the distal tip. Further, each graph shows asecond parabolic grind starting at approximately 4.8 cm from the distaltip. The uniform diameter core wire section is between the parabolicgrind sections, and there is a uniform diameter core wire sectionstarting at approximately 1.2 cm from the distal tip. The parabolicgrind profile shown in FIGS. 35 and 36 provide guidewires that have alinear change in stiffness, are flexible, and still maintain a highdegree of torque to the guidewire distal end to navigate tortuousarteries and other vessels.

Conventional materials and manufacturing methods may be used to form theparabolic grind profiles of the disclosed guidewires. Those skilled inthe art can use computerized grinding machines to form the parabolicgrind profiles disclosed herein.

While the invention has been illustrated and described herein in termsof its use as a guidewire, it will be apparent to those skilled in theart that the guidewire can be used in all vessels in the body. Alldimensions disclosed herein are by way of example. Other modificationsand improvements may be made without departing from the scope of theinvention.

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 13. A method of making a mold for use informing a solder joint, comprising: providing a mold; machining a cavityinto a first mold section and a second mold section; machining thecavity into a micro-J shape so that the cavity in the first mold sectionis a mirror image of the cavity in the second mold section.
 14. Themethod of claim 13, wherein the first mold section has a first face andthe second mold section has a second face, the first face and the secondface being configured to be removably attached.
 15. The method of claim14, wherein the micro-J shape has a distal section, and furthercomprising machining angular grooves in the distal section of themicro-J shape.
 16. The method of claim 15, wherein the angular groovesare machined in the first mold section and the second mold section andare mirror images of each other.